This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. De novo designed metallopeptides offer simplified constructs retaining sufficient complexity to be useful models of metalloproteins. In particular, models of Zn Carbonic Anhydrase (CA) and Copper Nitrite Reductase (CuNIR) can be synthesized using tri-stranded coil coiled with histidines in the metal binding site. Models of CA have shown interesting hydrolitic capabilities towards acetyl esters, and can be properly designed for the introduction of additional binding site for metals with structural roles without any interference with the catalytic active site. Models of CuNIR have shown the capability to bind carbon monoxide in a fashion analogue to that of the natural protein. The tuning of enzymatic activity, substrate binding and metal-centered redox potential can be tuned by making systematic changes in not only the first sphere coordination environment, but also the second sphere and beyond.